Exploration of ammonia resorption cycle for power generation by using novel composite sorbent

Abstract

Exploration of ammonia resorption cycle for power generation by using novel composite sorbent.Abstract: Expanded natural graphite and carbon coated nickel are selected as the additives in the development of novel composite sorbent. Improved thermo-physical properties of composite strontium chloride result in a faster sorption reaction rate than that without using carbon coated metal. A case study of ammonia-based resorption power generation cycle with two identical reactors is analyzed in terms of sorption characteristics of composite sorbents. Power could be generated in both half cycles, which greatly enhances working versatility and thermal efficiency. It is indicated that additive of carbon coated nickel has a positive influence on performance of resorption power generation cycles.Energy and exergy efficiency of basic resorption cycle range from 0.072 to 0.116 and from 0.402 to 0.737, respectively. Basis resorption cycle for power generation is also compared with improved resorption cycle by using different composite sorbents. Increment between improved and basic resorption cycle by using the sorbent without carbon coated nickel is larger than that using that with carbon coated nickel. Energy density by using novel composite sorbent is improved by up to 20% based on mass and volume of sorption reactor. Through reheating process, performance of basic resorption cycle is further improved by 3-5 times.

Novel hybrid thermochemical cycles for low-grade heat storage and autothermal power generation: A thermodynamic study

“…As stated in Section 3.1, a set of values considered as 'realistic' has been defined for the key simulation parameters: ηis = 0.8, ΔX = 0.8, τmet = 0.1, ΔTHX1 = 5 K, ΔTHX2 = 10 K and ΔTeq = 20 K. The results presented in Sections 4 and 5 were obtained under this 'real' set of parameters. However, since the existing literature on hybrid thermochemical cycles [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] usually relies on more optimistic assumptions (especially for temperature pinches), a fair comparison of the performances of the proposed cycle with other hybrid thermochemical cycles cannot be provided. Therefore, another set of parameter values (more optimistic) has been defined and simulations have been carried out under this 'perfect' set of parameters: ηis = 1, ΔX = 1, τmet = 0, ΔTHX1 = 0 K, ΔTHX2 = 0 K and ΔTeq = 0 K. In this section, the results obtained under the 'perfect' set of parameters are reported and a comparison with the 'real' case is provided.…”

“…Jiang et al [22] studied another experimental setup of a resorption power and cold cogeneration cycle and their work highlighted the technical difficulty of achieving a stable power output due to strong coupling between chemical reaction kinetics and the dynamics of the expansion process. They went on to propose an improvement of resorption cycles using a novel composite sorbent [23], and obtained energy efficiencies in the range 0.11-0.14 and exergy efficiencies from 0.62 to 0.81, with a heat source temperature between 80°C and 110°C and a heat sink (ambient temperature) at 30 °C. Finally, their recent work [24] highlighted how hybrid thermochemical cycles hold promising potential for low-grade heat utilization: using heat source temperatures in the range 200-360°C and a heat sink temperature of 35°C, their novel resorption cycle integrating internal heat recovery provided a refrigeration effect at 0°C with a COP of 1.3 and exergy efficiencies between 0.41 and 0.74.…”

Hybrid thermochemical cycles for low-grade heat storage and conversion into cold and/or power

“… For power production only, a resorption cycle implementing a novel composite sorbent was investigated by Jiang et al [10]. Using hot source at 80-110 °C and heat sink at 30 °C, its energy and exergy efficiencies range from 0.07 to 0.12 and from 0.40 to 0.74, respectively.…”

Investigation of thermal characteristics of strontium chloride composite sorbent for sorption refrigeration

“…The strontium chloride has been recommended as one of the promising chemisorption salt for low-grade heat recovery application and thermal energy storage [21,22]. For example, the authors have previously reported and investigated the potential application of using novel strontium chloride composite sorbent to form a power generation system [23]. Results indicated the developed system can be potentially used to recover low-grade heat sources such as solar energy, geothermal energy and industrial waste heat under the temperature over 120 o C [23].…”

“…For example, the authors have previously reported and investigated the potential application of using novel strontium chloride composite sorbent to form a power generation system [23]. Results indicated the developed system can be potentially used to recover low-grade heat sources such as solar energy, geothermal energy and industrial waste heat under the temperature over 120 o C [23]. However, compared with the reported researches on composite CaCl2 [24], limited quantitative data can be found for the sorbents using strontium chloride (SrCl2), which leads to the difficulty of generating a highly accurate simulation model to predict the performance of sorption system using SrCl2 sorbents.…”